Metallic pollutant used as "antiknock agent" in petrol is

Options

A. Benzopyrene
B. Tetraethyl lead
C. Zinc oxide
D. Aluninum oxide

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for a metallic pollutant that is used as an "antiknock agent" in petrol. An antiknock agent is a substance added to fuel to reduce engine knocking, which is a type of noise caused by premature combustion in the engine.

2. **Identifying the Options**: The options provided are:
- Benzopyrene
- Tetraethyl lead
- Zinc oxide
- Aluminium oxide

3. **Analyzing Each Option**:
- **Benzopyrene**: This is a polycyclic aromatic hydrocarbon and is not used as an antiknock agent.
- **Tetraethyl lead**: This is a well-known antiknock agent that was widely used in petrol to improve engine performance by reducing knocking.
- **Zinc oxide**: This is not used as an antiknock agent; it is more commonly used in other applications such as sunscreens and ointments.
- **Aluminium oxide**: This is also not used as an antiknock agent; it is primarily used in ceramics and as an abrasive.

4. **Conclusion**: Based on the analysis, the correct answer is **Tetraethyl lead**. It is a metallic compound that was used in petrol as an antiknock agent to reduce engine knocking.

5. **Toxicity Consideration**: It is important to note that tetraethyl lead is highly toxic and has been banned in many countries due to its harmful effects on health and the environment.

**Final Answer**: The metallic pollutant used as an "antiknock agent" in petrol is **Tetraethyl lead**.

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